Remove synthetic vsync from Android VsyncMonitor

ui/android/java/src/org/chromium/ui/VSyncMonitor.java

Index: ui/android/java/src/org/chromium/ui/VSyncMonitor.java
diff --git a/ui/android/java/src/org/chromium/ui/VSyncMonitor.java b/ui/android/java/src/org/chromium/ui/VSyncMonitor.java
index 0396135687390d44800967eec5e0b901c357820a..281ed143c3f9299d42878f97486f7119d7292708 100644
--- a/ui/android/java/src/org/chromium/ui/VSyncMonitor.java
+++ b/ui/android/java/src/org/chromium/ui/VSyncMonitor.java
@@ -51,8 +51,6 @@ public class VSyncMonitor {
     // If the monitor is activated after having been idle, we synthesize the first vsync to reduce
     // latency.
     private final Handler mHandler = new Handler();
-    private final Runnable mSyntheticVSyncRunnable;
-    private long mLastVSyncCpuTimeNano;
 
     /**
      * Constructs a VSyncMonitor
@@ -73,7 +71,6 @@ public class VSyncMonitor {
             @Override
             public void doFrame(long frameTimeNanos) {
                 TraceEvent.begin("VSync");
-                mHandler.removeCallbacks(mSyntheticVSyncRunnable);
                 if (useEstimatedRefreshPeriod && mConsecutiveVSync) {
                     // Display.getRefreshRate() is unreliable on some platforms.
                     // Adjust refresh period- initial value is based on Display.getRefreshRate()
@@ -88,16 +85,6 @@ public class VSyncMonitor {
                 TraceEvent.end("VSync");
             }
         };
-        mSyntheticVSyncRunnable = new Runnable() {
-            @Override
-            public void run() {
-                TraceEvent.begin("VSyncSynthetic");
-                mChoreographer.removeFrameCallback(mVSyncFrameCallback);
-                final long currentTime = getCurrentNanoTime();
-                onVSyncCallback(estimateLastVSyncTime(currentTime), currentTime);
-                TraceEvent.end("VSyncSynthetic");
-            }
-        };
         mGoodStartingPointNano = getCurrentNanoTime();
     }
 
@@ -137,7 +124,6 @@ public class VSyncMonitor {
         assert mHaveRequestInFlight;
         mInsideVSync = true;
         mHaveRequestInFlight = false;
-        mLastVSyncCpuTimeNano = currentTimeNanos;
         try {
             if (mListener != null) {
                 mListener.onVSync(this, frameTimeNanos / NANOSECONDS_PER_MICROSECOND);
@@ -151,31 +137,6 @@ public class VSyncMonitor {
         if (mHaveRequestInFlight) return;
         mHaveRequestInFlight = true;
         mConsecutiveVSync = mInsideVSync;
-        // There's no way to tell if we're currently in the scope of a
-        // choregrapher frame callback, which might in turn allow us to honor
-        // the vsync callback in the current frame. Thus, we eagerly post the
-        // frame callback even when we post a synthetic frame callback. If the
-        // frame callback is honored before the synthetic callback, we simply
-        // remove the synthetic callback.
-        postSyntheticVSyncIfNecessary();
         mChoreographer.postFrameCallback(mVSyncFrameCallback);
     }
-
-    private void postSyntheticVSyncIfNecessary() {
-        // TODO(jdduke): Consider removing synthetic vsyncs altogether if
-        // they're found to be no longer necessary.
-        final long currentTime = getCurrentNanoTime();
-        // Only trigger a synthetic vsync if we've been idle for long enough and the upcoming real
-        // vsync is more than half a frame away.
-        if (currentTime - mLastVSyncCpuTimeNano < 2 * mRefreshPeriodNano) return;
-        if (currentTime - estimateLastVSyncTime(currentTime) > mRefreshPeriodNano / 2) return;
-        mHandler.post(mSyntheticVSyncRunnable);
-    }
-
-    private long estimateLastVSyncTime(long currentTime) {
-        final long lastRefreshTime = mGoodStartingPointNano
-                + ((currentTime - mGoodStartingPointNano) / mRefreshPeriodNano)
-                * mRefreshPeriodNano;
-        return lastRefreshTime;
-    }
 }